GENERA AND SPECIES. EEY 
PLATE XLII. 
WOODSIA. Robert Brown. 
GEN. CHAR.—Fruit-dots roundish, scattered on the back of 
simply-forked, free veins; indusium attached under the sori, burst- 
ing at the top into numerous jagged segments. 
This genus, named in honor of Joseph Woods, an English 
botanist, author of the “ Tourists’ Flora,” is represented in 
this country by six species of small, tufted, pinnately-divided 
ferns, all of which, with a single exception, are properly 
northern species, though I have doubtfully added another, 
so as to include all the species likely to be found in this 
geographical region. The Woodsia is widely dispersed in 
temperate latitudes, extending in Europe from the East 
Indies to Great Britain, and, on the western continent, 
from British America to Peru, with the exception of the 
intermediate tropical region. 
The indusium, instead of covering the sori, as in nearly 
all the other ferns, is attached beneath them on the frond. 
While young, however, the sporangia are inclosed within 
the indusium, which forms a sort of cup. As the frond 
develops the cup-like indusium bursts open, forming in 
some species, after it spreads out, a number of articulated 
hair-like bodies composed of irregular cylindrical cells. 
Figure 1 represents the magnified portion of a frond; fig- 
ure 2, sori magnified; figure 3, spore magnified. Figures 
2 and 3 are from Hooker and Bauer. 
